1. Field
Example embodiments relate to methods and apparatuses for restoring properties of graphene.
2. Description of the Related Art
Examples of low-order nano substances formed of carbon atoms include fullerene, carbon nanotube, graphene, and graphite. Fullerene is a zero-dimensional structure formed in a ball shape by a hexagonal arrangement of carbon atoms, carbon nanotube is a one-dimensional structure in a roll shape, graphene is a two-dimensional structure of a layer of atoms, and graphite is a three-dimensional structure in a stack shape.
Graphene has stable and desirable electrical/mechanical/chemical characteristics. In addition, graphene has desirable conductivity, and thus, much research has been conducted on developing nano devices including graphene. However, in comparison with silicon in a bulk form, graphene is sensitive to external factors, and thus, its unique structure is easily changed by contact with O, H, or H2O. When used in an electronic device, graphene inevitably comes in contact with a resist residue due to mask patterning. Such contamination of graphene may alter the properties of graphene, e.g., a charge neutrality point, a doping state, carriers (electrons and holes), or conductivity. In this regard, graphene cleaning, e.g., thermal annealing, electrical current annealing, and solvent treatment using chloroform, has been proposed.
However, because thermal annealing is performed slowly at a relatively high temperature from about 200° C. to about 500° C. for about 2 hours to about 4 hours, devices including graphene may be damaged. Moreover, a polymer residue may not be completely removed by thermal annealing. Also, electrical current annealing merely allows local-area annealing of graphene. Furthermore, chloroform treatment is not recommended from an environmental point of view because chloroform is a toxic anesthetic.